The invention relates to video animation techniques, and particularly to high speed production of animated programs formed in turn of a selected succession of still images, utilizing high speed electronic edits on a videotape recorder.
The continually on-going development of more sophisticated, high speed videotape recorders has resulted in a corresponding increase in the number and types of applications in which the recorders are particularly suited. One such field in which videotape recorders are finding increasingly more use, and which field until recently has been relegated to the film industry, is in the area of recording and playing back still pictures, and more particularly in the recording of preselected successions of still video images. Such a technique for recording and reproducing a succession of still images is commonly known in the art as an animation process, with the recorded material being known as an animated program. Currently in the video recording field there is increasing demand for animation and, in particular, for improved techniques for generating animated programs in the areas of, for example, advertising and cartoons. However, these well known fields of animation are only a small area of a presently increasing sphere of interest, wherein animation techniques may be advantageously applied.
To illustrate, the military forces and industry in general have found a need for animation in providing instructional material for educational purposes, employing the use of the television medium. In such fields, instructional material used for learning processes readily may be recorded by the animation technique, utilizing a video camera and a videotape recorder to transfer a page of the instructional material onto one frame or field in the video tape medium, which then may be shown in stop motion during instruction. Thus large numbers of pages from an instruction or maintenance manual may be reconstructed into an animated program on video tape, along with any introduction and/or explanatory remarks and art work such as title blocks, required in the course of instructing a class via the television medium.
Still another area of increasing need for animation is the field of mastering of video discs. Although not involved in animation per se, mastering of video discs currently is a very laborious process involving either the use of multiframe stores or the transfer of images from film. Animation techniques and videotape equipment would greatly speed the mastering process by providing an animated video master on video tape onto which audio may be dubbed to produce a finished video tape which is used to make laser video discs.
At present, the most obvious need for animation is in the field of entertainment wherein several well known companies produce cartoons, as well as animated full length features for showing on television. In addition, animation techniques are widely employed by video promotional companies to provide station identification material, animated programs for commercial advertising and/or other animated promotional features and material.
In the production of animated programs, the entire plurality of still pictures which together form the program, generally are prepared prior to performing the recording process, regardless of the recording medium or technique used for recording. Until very recently, material for cartoons and promotional features have been prepared by a process generally known as hand-drawn art. In generating hand-drawn art, an animator draws an outline of the still image or picture of every image in the entire program. The drawings then are passed to another animator (termed an "in-betweener") who draws the picture outlines of the in-between images. The complete succession of outline drawings then are passed to people who color in all the outlined images. The complete animation program material is then ready to be recorded on film, video tape or other medium capable of providing playback of the succession of recorded images as a continuous animated program. Until recently, such animated programs have been mastered onto film which then is developed and shown via, for example, a film projector. It follows that animation techniques employing hand-drawn art coupled with film recording schemes require prohibitive amounts of labor, have become extremely expensive, and lack flexibility.
However, there has been substantial development in the computer graphics field, which provides artists a more convenient means for generating the still images required for assembling animated programs. Furthermore, computer graphics systems such as the Ampex Video Art (AVA-3) graphics system manufactured by the Ampex Corporation, Redwood City, Calif., supply the images in the form of video signals which accordingly can be recorded by a videotape recorder without further processing. Such graphics systems facilitate the rapid generation of still pictures. However, the combination of such a computer graphics system with present videotape recorders requires some form of control interface to allow the efficient transfer of the animation material to the videotape recorder.
In the field of animation, a term and corresponding operating parameter commonly used is "cel", which is an art unit formed of the same still image or picture recorded a selected number of times. Thus, given the hand-drawn cartoon art of previous mention, if a "cell size" of four pictures is selected, each of the pictures drawn by the animators is exposed on film four times. Thus only one-fourth of the art material is required to produce the same length animated program with, however, an attendant loss in quality of animation. Thus, increasing the duration or size of the cell, decreases the cost of generating and recording the animation material, whether recorded on film or video tape mediums, but also decreases the quality of the program. In various fields such as cartooning, the compromise is acceptable.
In this age of sophisticated high speed videotape recording techniques and apparatus, it is obvious that the use of film techniques and apparatus for generating animated programs is relatively inefficient and becoming obsolete. Furthermore, at present there are no control interfaces available for efficiently coupling a computer graphics device to a videotape recorder to record animated programs. It follows that it would be highly desirable to provide an efficient high speed technique and apparatus for generating animated programs, or for recording large pluralities of discontinuous pictures, in a video tape medium, either in real or non-real time.
Current techniques utilizing videotape recorders and their associated editing techniques, generate animated programs by recording each still image only once as a single field or frame of video. Since the recorders are capable of performing only conventional editing processes, they are incapable of using the "cel" recording technique of previous mention commonly employed to cut costs, improve the speed of program production, etc. In such conventional techniques, hand-drawn art is viewed by a video camera and recorded on video tape, or computer generated images are recorded directly on the video tape. Such systems include a "black box" control interface which provides standard edit control signals operable by the animator, wherein each video signal corresponding to a single piece of art, is recorded singly. The animator selects the use of a field or frame for recording each image, enters the condition into the recorder's edit memory, and instructs the machine to preroll to its normal cue point. The transport is stopped, and then is accelerated forward to normal record speed while the off-tape sync information is synchronized to the incoming video signal. The animator then performs the edit by recording the video image at the edit entry point a single time, whereupon he exits, and completes the postroll, rewind and review of the recorded image if desired. In situations where only short program segments are generated, such a technique is more efficient than the use of film and film techniques. However, in the generation of animated programs where each production may require thousands or many tens of thousands of edits for a one hour production, the use of such a standard editing process to record each and every still image, is extremely time consuming.
In a further sophistication of the technique employing the black box control interface, one or more electronic storage devices capable of storing still video images also are utilized, wherein the images subsequently are retrieved and supplied to a videotape recorder in real time. Such scheme also uses conventional edit techniques, cannot employ the cell concept of recording, and thus has the same disadvantages, while further requiring the use of one or more large and expensive video image storage devices.
There presently is available a videotape recorder specifically designed and manufactured for generating animated programs, with specific animation controls being built into the recorder. Such a specialized recorder, however, records in still frame, i.e., records a still video image with the tape stationary. Such apparatus fails to produce a standard type-C format if the recording is done with a non-movable record head such as existing in standard videotape recorders. To provide a type-C format, this videotape recorder employs a special moveable record head, and requires the application of special head tracking voltages, in order to selectively move the head to record a type-C format while the tape is stationary. This highly specialized apparatus requires a control track to provide cueing and thus requires a prerecorded tape to allow recording in the insert edit mode. Thus assembly editing generally is not available. In addition, in the moveable record head configuration, the frame of video is recorded on the video tape by first deriving a head tracking signal based on the playback of a previously recorded signal track on the tape while the tape is stationary. The head tracking signal is stored in storage means, whereupon it is supplied to the recording head during the single recording of a subsequent video image to cause the record head to follow the prior track while recording the next image a single time on the stationary tape. Such a special tracking record head configuration is not available in present videotape recorders, and is an unnecessarily complex addition to the recorder. In addition, the recorder cannot use the cell concept of recording a still image a selectable number of times, but must be recued after recording a still image a single time.
Accordingly, as previously discussed, it would be highly desirable to provide an animation technique employing video tape recording techniques wherein multitudes of single frame edits may be made with a minimum of operator intervention, wherein the recorder has the ability to automatically sequence the edit points to allow for more rapid and efficient recording of the animated program.
The present invention circumvents the disadvantages and the problems of the previously mentioned techniques and associated apparatus presently used for generating animated programs on video tape. To this end, an animation edit technique and apparatus is provided which is particularly adaptable to present sophisticated videotape recorders to provide high speed automated recording of animated programs on video tape. The invention provides for the rapid recording of large successions of still images in the "cel", configuration of previous discussion, wherein a "cel" is a video recording unit of a selectable number of video frames or fields of the same piece of material. That is, the same still image recorded a selectable number of times is hereinafter defined as a "cel". The present apparatus provides an animated program in true SMPTE and EBU type-C format, and is capable of recording in both the assemble and insert edit modes, unlike the special animation videotape recorder described above. The recording is made at normal recording speed and thus may be implemented as an integral part of, or an adjunct control panel for, a conventional videotape recorder having a stationary record head and a moveable tracking playback head. Thus the present animation apparatus does not require tape transport modification or prerecorded video tapes in order to produce an animated recording. The cell size readily is selectable to provide added flexibility in generating different types of animated programs. Recording in terms of cel size or duration further provides the advantage of allowing the automated determination of both the entry and exit points of subsequently recorded cels, prior to performing the actual recording, wherein recording a cel of multiple frames or fields is done without having to recue the transport after recording each frame or field of the cel.
In a manually operated configuration, the system provides relatively high speed animation recording with a simple pushbutton input by an operator at the recorder control panel or at a remote location. In an automated embodiment, the entry and exit points of the succession of cels which define program segments may be preselected and programmed into an "edit decision list" or "script", to allow the recorder to automatically record the animated program with a minimum of operator attention. The system readily lends itself to a non-real time hand-drawn art technique, and is particularly adaptable to computer generated graphics systems wherein still images may be dynamically generated and supplied to the recorder in real or non-real time.
To this end, an animate software package and hardware additions provide an animate operating menu with associated animate controls and displays. The hardware includes entry and exit time storage registers, which by way of operator modifiable SMPTE time code or control track tape time information, address the edit entry and exit points, with the resulting numbers in the registers being displayed in respective display areas of the animate menu display on the control panel. A cel size register and respective display of the contents allow an operator to view and modify the cel duration or size in SMPTE time code or control track tape timer information. In addition, a "done" register accumulates and similarly displays a total number of frames or fields in terms of the number of cels which have been recorded. The "done" register is presetable and is updated in accordance with the changes in the entry register content in the course of the recording process, to indicate the accumulated total of cels recorded. A cel count register may be used to count down from an initial total number of cels to be recorded, to indicate thus the end of a preselected program segment or of the entire animated program. This adds flexibility of use in that the edit sequence may be automated, which adds to the convenience of the present animation process.
In operation, the animate operating menu is called up, and key parameters such as an initial edit entry location and cel size are input to the recorder. On command, the first cel is recorded, whereupon the process automatically sets up the next cel recording event by calculating the next edit entry and exit points. The recorder automatically is recued to the calculated next entry point and the process continues. In the manual scheme, the operator presses a pushbutton to generate an animate edit start command which initiates the recording of each cel. In the automated scheme, an animate edit done tally command is sent to the graphics system after a cel is recorded, to increment the latter to the next still image. When the next still image is available, the graphics system sends the animate edit start command and the next cel is recorded. Thus, with simple interfacing to existing animation material generating systems or sources, such as computer graphics devices and animation tables, the animation process and apparatus operates in selectable degrees of automation.